Stefanie Martini has been tapped to play Jane Tennison’s younger self, stepping in to the shoes of Oscar-winning actress Helen Mirren, who originated the role in 1991, and continued making Prime Suspect episodes off and on until 2006.

Martini most recently starred inJulian Fellowes’ post-Downton Abbeyperiod drama Doctor Thorne, in she played the young woman from rather unfortunate financial circumstances who lives with her uncle (the titular Doctor Thorne) and falls in love with son from the rather rich aristocratic family next door. The rest of the cast features Sam Reid and Blake Harrison as Jane’s superiors, DCI Len Bradfield and DS Spencer Gibbs, with veteran actor Alun Armstrong as the head of a local crime family.

The six-part prequel series is being written by Prime Suspect CreatorLynda La Plante, and will reveal how Tennison became such a complex and formidable character in the Metropolitan police.

Set in 1970s Hackney, it will see Tennison start as a WPC on the beat before being thrown into a brutal murder enquiry. Viewers will also meet her family and gain an insight into her personal life before her time as a detective in Prime Suspect.

Filming on the new prequel series is already under way.

There’s no set air date yet for Tennison, but since Prime Suspect is about to celebrate the 25th anniversary of its premiere toward the end of this year, around that window of time seems like a pretty safe guess.

Does Tennison sound like something you’d watch? How do you feel about the prospect of a Prime Suspect prequel? (After all, Endeavour did turn out pretty well!) Let us know in the comments.

Digital media type by day, Lacy has a fairly useless degree in British medieval literature, and watches entirely too much television in her free time. Ninth Doctor enthusiast and all around Whovian evangelist. Say hi on Twitter at @LacyMB.